One or more embodiments of the invention relate to a steering column arrangement, a casing tube for a steering column assembly, and a vehicle having a steering column assembly.
There are known steering column arrangements that have a steering spindle and a casing tube enclosing the steering spindle (from EP 1 572 519 B1 and DE 10 2007 060 631 A1). The steering spindle is mounted such that it can be rotated about a longitudinal axis relative to the casing tube. A switch module is provided, which typically has a housing and a fastening sleeve provided largely centrally on the housing in the form of a spring cage, and the fastening sleeve being compressible in the radial direction. The spring case encloses a plug-in opening of the housing for the casing tube, so that the switch module can be mounted on the latter and can be securely clamped to the casing tube. The plug-in opening of the housing is flush with the screw opening for a steering wheel bolt, which is screwed in coaxially in the housing from the side lying opposite the spring cage. An inner side of the housing limiting the plug-in opening is slightly widened conically in the direction of the casing tube, and lies on a negative-mold outer side of the spring cage. At its end facing the steering wheel, the spring cage has stop lugs extending radially inward, which impart a defined axial position to the cage when it is mounted on the casing tube. For installation, initially, the housing with the spring case is mounted on the casing tube, and then after mounting on the steering wheel, the steering wheel bolt is tightened, causing the housing to be displaced axially in the direction of the casing tube and relative to the spring case. Based on the conicity of the spring cage outer side and the housing inner inside, the displacement develops the effect of a wedge gear, where its springs grip the casing tube. In addition, small, knifelike projections are provided on the springs, which hook onto the projections. In that the switch module is fixed securely to the casing tube, axial fixation of the latter relative to the casing tube is achieved. In order to arrange the switch module even in a defined angle position—viewed in the circumferential direction—relative to the casing tube, spring-loaded arresting blocks are inset in the spring cage and submerge when the switch module is in plug-in position into axial, elongated holes of the casing tube. If the spring cage is compressed in the radial direction during installation, at the same time, the arresting blocks are also depressed into the elongated holes of the casing tube, assuring anti-twist locking of the switch module on the casing tube in the radial direction. Altogether, the switch module is thus arranged in a play-free manner on the casing tube viewed in the axial and the circumferential directions.
A disadvantage of the above-known steering column arrangements is that fact that the arresting blocks require a large installation space in the housing, so that at the same time, the installation space available for the casing tube is reduced. As result, the stiffness and the natural frequency of the casing tube is limited, which necessitates additional arrangements in order to assure steering comfort for the driver of a vehicle fitted with the steering column arrangement. Thus, if possible, no perceptible vibrations must arise.
Moreover, an anti-twist connection of a steering column switch with a fixed casing tube is known from DE 20 2006 015 310 U1. The known steering column switch has two protrusions axially arranged one behind the other that engage with two grooves of the switch housing, where one of the two protrusions serves as a positioning aid, while the other protrusion with the corresponding groove of the housing forms the largely play-free anti-twist lock. Outside of this connection area, the housing is pressed by means of a tensioning clamp against the casing tube such that an axial displacement of the housing in the direction of the end of the casing tube is prevented.
The present invention is directed a steering column arrangement, a casing tube, and a vehicle in accordance with one or more embodiments of the disclosure that do not have the above-described disadvantages and solve the above-problems. In particular, play-free and precisely aligned installation of a switch module on the casing tube should be possible, where the casing tube at the same time has adequately high stiffness and natural frequency in order to assure sufficient steering comfort for a vehicle driver.
The steering column arrangement has a steering spindle and a casing tube enclosing the steering spindle. The steering spindle is mounted such that it can be rotated about a longitudinal axis relative to the casing tube. Moreover, the steering column arrangement has a switch module that in turn has a housing and a fastening sleeve provided on the housing. The fastening sleeve is designed so that the switch module with the fastening sleeve can be mounted on the casing tube and securely clamped to the latter. The steering column arrangement includes the casing tube that has at least radial projection on an outer circumferential surface. Additionally, the fastening sleeve has on an inner circumferential surface at least one—viewed in the longitudinal direction—guide groove, the radial projection meshing with the guide groove when the switch module is mounted on the casing tube. The axial fixation of the switch module on the casing tube is carried out by securely clamping the fastening sleeve on the casing tube. Anti-twist locking is now effected, however, in that at least one projection provided on the casing tube, which projection projects from an outside circumferential surface of the latter, meshes with a guide groove, which is provided on an inner circumferential surface of the fastening sleeve. The fastening sleeve is preferably designed to be free of arresting blocks, which provide alignment in the circumferential direction. The function of the arresting blocks usually provided on the fastening sleeve or the spring cage now is assumed by the casing tube, in particular, by its at least one radial projection, so that the receiving spaces otherwise provided for the arresting blocks in the housing can be omitted. In at least that regard, the casing tube can be designed with a larger diameter, which allows a significant increase in stiffness and a rise in its natural frequency. The at least one projection on the casing tube can thus be made comparatively compact, and requires little installation space. The steering column arrangement of the disclosure implements a play-free and aligned connection between the switch module and the steering column that also withstands constantly high torques.
A longitudinal direction or an axial direction means a direction that runs parallel to the axis of rotation of the steering spindle, and preferably, coincides with the latter. A radial direction is vertical to the longitudinal direction. A circumferential direction means a direction which concentrically encloses the longitudinal direction.
Preferably, the steering column arrangement is provided for use in a vehicle, such as a motor vehicle. To this end, preferably a steering wheel can be connected to the steering spindle, in particular, can be mounted on a torque-transmitting structure of the steering spindle, for example gearing, and can be secured to the steering spindle with a steering wheel bolt.
In accordance with the invention, in addition, the guide groove—viewed in cross section—has a trapezoidal contour. As such, the side walls of the guide groove, extending in the longitudinal direction, at least in areas are not oriented in parallel to one another, but rather run transversely to one another, where their separation decreases radially outward, thus to larger radial separations from the longitudinal direction. The side walls of the guide groove are substantially oriented parallel to one another, where, however, at one end of the side walls a chamfer is provided at the groove base, so that in this area transverse wall segments result. The trapezoidal contour of the guide groove has the advantage that when there is compression of the fastening sleeve, the long sides or long edges of the projection, which run in the longitudinal direction of the casing tube, are clamped by the transverse side walls or the wall sections of the guide groove. This is a great advantage in comparison with the above-known arrangements, in which an arrester block held in the housing of the switch module engages a groove in the casing tube, because with such a solution, no corresponding clamping effect is attainable, so that radial play cannot be completely eliminated. On the contrary, only inadequate elimination of the radial play occurs. By way of the setup of the disclosure, the transverse side walls or wall sections on the elongated contour of the projection create a stiffer positioning of the switch module on the casing tube and thus also an increase in the natural frequency of the steering column arrangement.
In an exemplary embodiment of the steering column arrangement, the fastening sleeve is arranged on the housing, in particular secured to the latter. The housing is particularly designed as a plastic housing, the fastening sleeve preferably including a metal or a metal alloy, particularly including a metal or a metal alloy. Another exemplary embodiment is directed to the fastening sleeve that is designed as a single piece with the housing or as part of the housing.
In another exemplary embodiment of the steering column arrangement, the fastening sleeve—viewed in the radial direction—is compressible. Preferably, it is configured as a spring cage. In particular the fastening sleeve particularly is essentially cylindrical, where on a side facing toward the casing tube and facing away from the steering wheel, it has at least one longitudinal slot so that at least two spring tabs divided by the longitudinal slot are formed on the fastening sleeve. The spring tabs—viewed in the radial direction—can swivel. With the spring tabs, the fastening sleeve can be securely clamped to the casing tube. Toward this end, the fastening sleeve preferably has an inner diameter that is slightly larger than an outer diameter of the casing tube, so that the fastening sleeve can be mounted on the casing tube without clamping and then can be securely clamped on the latter by radial compression.
Alternatively, the fastening sleeve can carry at least two, preferably three or even more clamping jaws, with which the switch module can be securely clamped to the casing tube.
Preferably, the fastening sleeve has a stop at its end, which in plugged-in state faces a steering wheel, in particular at least one stop lug extending inward in the radial direction. The stop is provided in order to impart a defined axial position to the fastening sleeve during mounting on the casing tube. It is also possible that the fastening sleeve has an annular collar, which defines the stop on one end of the casing tube facing the steering wheel in plugged-in state. It is also possible that the fastening sleeve has multiple stop lugs, preferably at least three stop lugs.
The radial projection on the casing tube is preferably designed as a bump-like elevation. Moreover, the radial projection and the guide groove are preferably adapted to one another such that they already interlock with the casing tube during mounting of the fastening sleeve, so that the switch module on the casing tube is already secured in the circumferential direction before being securely clamped. In another example, the radial projection interlocks with the guide groove essentially play-free or entirely play-free, so that the switch module on the casing tube—viewed in the circumferential direction—has essentially no play or no play at all.
This freedom from play is very important, not only for the driver's steering comfort, but also essentially to assure the functionality of a steering angle sensor preferably integrated into the switch module. This is a substantial component of a fatigue recognition system preferably provided in the vehicle, which is designed to identify driver fatigue and to warn the driver in a timely manner. Therefore the arrangement of the switch module on the casing tube, as play-free as possible (preferably entirely play-free)—viewed in the circumferential direction—is also important for vehicle safety.
An exemplary embodiment of the steering column arrangement that is distinguished by the fact that the projection has an elongated shape is preferred. This means that the length of the projection in the longitudinal direction is greater than the length of the projection in the circumferential direction. The projection is thus longer than it is wide. Preferably its length is at least double that of its width or preferably at least three times. This ensures that forces directed into the projection acting in the circumferential direction are picked up reliably and stably by the latter, which increases the precision of the fixation of the switch module arrangement on the casing tube—viewed in the circumferential direction—and also increases the stiffness of the arrangement.
An exemplary embodiment of the steering column arrangement is also preferred that is distinguished by the fact that the projection is designed as a single piece with the casing tube. Preferably the projection is stamped on the outer circumferential surface, in particular stamped from the inner to the outer direction, partially punched, or molded. The projection may thus be presented on the casing tube in an especially simple and economical manner, without requiring additional method steps for installation of the projection and an extra logistical expense for storage and installation of separate elements.
In yet another exemplary embodiment of the steering column arrangement, the projection is alternatively secured as a separate element to the casing tube. In particular, the projection is soldered, welded, glued, or secured in some other suitable manner, or in particular to the outer circumferential surface of the projection. The projection may include plastic or is made of plastic, where in particular it is secured using a plastic spray or in particular on the outer circumferential surface, and consequently, it is sprayed on. The two-part embodiment of the casing tube and the projection allows a different material selection for these elements, so that the materials used can be adapted to different tasks and functionalities of the elements. Moreover, the shape of the projection may be defined even more precisely if the latter is made as a separate element, and subsequently joined to the casing tube or secured on the latter. Preferably, an exemplary embodiment of the steering column arrangement includes the casing tube that has at least two projections. This improves the support from forces acting in particular in the circumferential direction, and generally leads to a more stable connection between the casing tube and the switch module.
Preferably, at least two projections—viewed along a diameter line of the casing tube—are arranged opposite one another. The casing tube then has at least two diametrically opposite elevations. This has the advantage that torques directed from the switch module to the casing tube, or vice versa, are especially uniformly transmitted. Such an embodiment is especially preferred if a vehicle cockpit enclosing the steering column arrangement protrudes into the passenger space in such a way that installation of the switch module is possible only in one position, so that no further definition of the position is needed.
Additionally, the at least two projections are preferably arranged such that—when viewed in the circumferential direction—they are offset with respect to one another. Here, in particular—measured in the circumferential direction—they have an angle between them that differs by both 0 degrees and 180 degrees. This has the advantage, based on the offset and the symmetry calculation implemented, that only a single installation option for the switch module on the casing tube exists. If the casing tube includes more than two projections, these are generally preferably distributed asymmetrically over the circumference of the casing tube. Here, the two projections may be diametrically opposite one another, and a third projection may be provided with an offset. If exactly two projections are provided, they preferably have only a slight offset from the diametric arrangement, so that although owing to the symmetry calculation, only a single installation option exists; at the same time, uniform torque conduction from the switch module to the casing tube is ensured.
Alternatively, at least two projections are provided, where the projections—viewed in the longitudinal direction—are arranged offset from one another. There is thus—possibly additionally to offset in the circumferential direction and/or a diametric arrangement—a displacement provided in the longitudinal direction, so that there is an axial elongation of the support between the switch module and the casing tube. Forces or torques that arises are thus distributed over a longer length area from the switch module to the casing tube, or vice versa, causing generally better support and a stiffer arrangement.
Preferably, the fastening sleeve has at least two guide grooves, where a projection is assigned to each guide groove. The projections offset with respect to one another in the circumferential direction and/or longitudinal direction thus preferably each mesh with a guide groove of the fastening sleeve assigned to it—e.g., those lying opposite to it in the radial direction.
In another exemplary embodiment of the steering column arrangement, at least two projections are provided which—viewed in the longitudinal direction—are arranged behind one another without an offset in the circumferential direction, so that they interlock with the same guide groove of the fastening sleeve. This especially promotes elongated support of the switch module on the casing tube, causing especially high stiffness.
There is especially favorable fastening with high stiffness when a plurality of longitudinal projections are offset with respect to one another on the casing tube axially and/or in the circumferential direction, and interlock with the accordingly assigned guide grooves on the fastening sleeve. Preferably, at least two projections are provided that are offset with one another in pairs only in the longitudinal direction, but not in the circumferential direction. Moreover, preferably at least two projections are provided, which are offset in pairs with respect to one another only in the circumferential direction, but not in the longitudinal direction. Preferably, at least two projections are provided that are offset with respect to one another in pairs both in the circumferential direction and in the longitudinal direction.
In an exemplary embodiment, the guide groove—viewed in cross section—has a trapezoidal contour. This means that the side walls of the guide groove, extend in the longitudinal direction, at least in areas that are not oriented in parallel to one another run transversely to one another, where their separation decreases radially outward, thus to larger radial separations from the longitudinal direction. The side walls of the guide groove may be substantially oriented parallel to one another, where at one end of the side walls a chamfer is provided at the groove base, so that in this area transverse wall segments result. The trapezoidal contour of the guide groove has the advantage that when there is compression of the fastening sleeve, the long sides or long edges of the projection, which run in the longitudinal direction of the casing tube, are clamped by the transverse side walls or the wall sections of the guide groove. This is a great advantage in comparison with the known arrangement, in which an arrester block held in the housing of the switch module engages a groove in the casing tube, because with such a solution, no corresponding clamping effect is attainable, so that radial play cannot be completely eliminated. On the contrary, only inadequate elimination of the radial play occurs. The transverse side walls or wall sections on the elongated contour of the projection create a stiffer positioning of the switch module on the casing tube and thus also create an increase in the natural frequency of the steering column arrangement.
The clamping force on the projection—especially when there are a plurality of projections that are offset with respect to one another in the axial and/or in the circumferential direction—may be so great that further clamping by spring tabs of a spring cage is no longer needed. In particular, there is then no need for projections that are normally radially inward on the spring tabs, which hook onto the casing tube at points. Rather, only the creation of the compressible fastening sleeve with the guide grooves formed on it is necessary, where the clamping of the projections in the guide grooves effects a more stable and elongated support—viewed in the longitudinal direction—than is the case when the spring tabs are supported at points on projections that are arranged radially inward on them. Thus, not just fixation in the circumferential direction is improved and made free of play, but the axial fixation is also rendered more reliable and secure.
An exemplary embodiment of the steering column arrangement includes the switch module that has at least one arresting block, which interlocks from the radial outer direction with the at least one guide groove and—viewed in the radial direction—is displaceably mounted. Here, the arresting block is spring-loaded radially inward and thus, is along the longitudinal axis and preferably pre-tensioned, where it interacts with the projection for axial arresting of the switch module on the casing tube. Here, preferably, the at least one arresting block is held or mounted in the housing of the switch module. The arresting block in particular serves to prevent dropping from the casing tube during installation of the switch module. If the switch module is mounted on the casing tube, the arresting block, which preferably is held on the housing on the inside, prevents the switch module from falling out of the casing tube before it is securely clamped to the latter. Toward this end, preferably it is provided that the arresting block snaps behind at least one projection of the casing tube when pushing together the switch module and the casing tube. When they are pushed together, the arresting block, which is spring-loaded or pre-tensioned in the radial direction, is raised by the projection, where—viewed in the longitudinal direction—it falls back behind the projection to its relaxed or pre-tensioned additional position. Thus, generally it executes a radial stroke movement.
Preferably, a first transverse surface with relatively gentle slope is provided on the arresting elements to facilitate the lifting movement; preferably, the transverse surface is complementary with a front first contact surface of the projection. When the switch module is pushed onto the casing tube, the first transverse surface slides on the first contact surface, where the arresting element—viewed in the radial direction—is raised. On its side—viewed in the longitudinal direction—facing away from the first transverse surface, the arresting element preferably has a second transverse surface with a much steeper slope, which makes a withdrawal movement of the switch module from the casing tube more difficult. In addition, the projection preferably has on the side facing the arresting element in the plugged-in state an accordingly steeper second contact surface, so that generally plugging in the switch module is much easier than pulling it out. In this manner, by snapping the arresting element behind the projection, an at least first retention of the switch module on the casing tube is affected, before the switch module is securely clamped on the casing tube. Preferably, the switch module has a plurality of arresting elements, which interact with a plurality of projections for axial locking of the switch module on the casing tube.
In a preferred exemplary embodiment of the steering column arrangement, the arresting element is attached with a pin which—viewed in the radial direction—is displaceably guided in the housing. The pin is arranged and designed in such a way that it engages outward through a through-hole of the housing when the arresting element—viewed in the longitudinal direction—is arranged at the height of the projection, and that it does not engage through the through-hole when the arresting element—viewed in the longitudinal direction—is arranged in front of or behind the projection. Preferably, the arresting element is formed by an arresting block, on which a pin is secured at the top, which is guidably mounted in a bushing arranged on the inside of the housing or on a double bearing. The pin preferably has a stop which keeps it from dropping out of the bushing or bearing. Preferably, the pin has a compression spring which is supported on one side on the arresting block and on the other side on the bushing or the inner bearing of the double bearing.
The through-hole is configured on the housing of the switch module and is flush with the pin, and its diameter preferably is greater than the end of the pin opposite the arresting block. If the switch module is mounted on the casing tube and if the arresting element executes its radial stroke movement in contact with the projection, at the same time, the pin secured to the arresting element also executes a radial stroke movement. Here, the end of the pin passes through the through hole of the housing and from the outside becomes visible to a workman. Behind the projection—viewed in the longitudinal direction—the arresting block and thus also the pin again falls back into the housing when it snaps behind the projection. Preferably, the pin with its end facing away from the arresting element precisely aligns with through hole. Preferably, the end of the pin opposite the arresting element is color marked.
A workman who plugs the switch module onto the casing tube can thus see from the pin, hear from the snapping sound, and feel by touch when the right installation position, that is, the right relative position of the switch module with respect to the casing tube and thus also to the steering spindle, is achieved.
If the correct relative position is achieved, the switch module can be securely clamped to the casing tube.
The correct installation position can thus be reported to a worker by touch, by sound, and by appearance, without the use of additional fastening means or rotating installation parts.
In an exemplary embodiment of the steering column arrangement, the switch module has a wedge gear by way of which the fastening sleeve can be securely clamped to the casing tube. In this case, the housing preferably has a first wedge surface, where the fastening sleeve has a second wedge surface, and the wedge surfaces are arranged with respect to one another and oriented in such a way that the fastening sleeve is securely clamped to the casing tube when the housing, relative to the fastening sleeve and relative to the casing tube, is displaced in the direction of the longitudinal axis by an end of the steering spindle facing a steering wheel. The switch module can then be clamped on the casing tube, during which the workman mounts the steering wheel on the steering spindle and tightens the steering wheel bolt, and causes the above-described relative motion between the housing and the fastening sleeve, whereby the latter is radially compressed and thus clamped onto the casing tube. This preferably is carried out to the point of absolute absence of play—viewed in the circumferential and longitudinal direction—between the switch module and the casing tube.
The fastening sleeve is provided on the housing preferably such that it is displaceable relative to the housing, or in particular, is arranged on the housing or secured to it. In particular, the fastening sleeve and the housing are preferably connected to one another in such a way that—in the longitudinal direction—they are a relatively displaceable with respect to one another. In this case, a displacement of the housing relative to the fastening sleeve is possible, in which a first wedge surface of the housing slides onto a second wedge surface of the fastening sleeve, so that altogether a wedge gear is implemented, which radially compresses the fastening sleeve and thus is clamped on the casing tube.
Alternatively, another exemplary embodiment is directed to the switch module having a clamping ring for securely clamping the fastening sleeve. The clamping ring is then preferably arranged on an end of the fastening sleeve facing away from the steering wheel and is tightened securely in order to compress the fastening sleeve—viewed in the radial direction—and securely clamp it to the casing tube. In one exemplary embodiment of the steering column arrangement, in which a clamping ring is provided for securely clamping the fastening sleeve, the fastening sleeve may be securely fastened to the housing, and in particular, may be connected to the latter in such a way that no relative displacement is possible between the housing and the fastening sleeve. In particular, it can be secured in a single piece with the housing or rigidly secured to the latter by screwing or in some other suitable manner. In this case, no relative displacement between the housing in the fastening sleeve is needed, because the fastening sleeve is radially compressed by the clamp ring and securely clamped to the casing tube.
The problem is also solved by creating a casing tube in accordance with one or more features of the disclosure. The casing tube is in particular configured for use in a steering column arrangement in accordance with one of the above-described exemplary embodiments. For example, the casing tube has at least one radial projection on an outside circumferential surface. The projection preferably is longitudinal. Here, the advantages already described in connection with the steering column arrangement with regard to the casing tube are implemented.
Additionally, the problem is solved by creating a vehicle in accordance with one or more features of the disclosure. The vehicle includes a steering column arrangement in accordance with one of the above-described exemplary embodiments. Here, the advantages already described in connection with the steering column arrangement are implemented in connection with the vehicle. The vehicle preferably is a motor vehicle.